The invention relates to connection arrangements for connecting two tube pieces of a crossmember for a vehicle. Further, the invention relates to crossmembers for vehicles having such a connection arrangement.
From the document WO 2008/034522 A1, a connection arrangement is known which has an attachment element in the form of a socket, which consists universally of the same material and at the longitudinal ends of which tube pieces are inserted, these being adhesively bonded to the socket in order to thus produce the crossmember.
The connection arrangement according to the invention and the crossmember according to the invention can be used, in particular as a component of a motor vehicle body, without loss of generality. As part of the motor vehicle body, the crossmember is arranged between what are known as the A-pillars in the region underneath the windscreen, running approximately horizontally. The crossmember serves for fastening the dashboard, the crossmember additionally stiffening the dashboard, which usually consists of plastic.
The crossmember has to have a high flexural rigidity, not only owing to its function of bracing the dashboard, but also on account of its function as a vehicle body component. A high flexural rigidity of the crossmember contributes not only ultimately to an increased safety of the motor vehicle and to protection of the occupants in the event of an accident. On the other hand, it is desirable nowadays to save weight in the case of body components in order to lower the energy consumption of motor vehicles.
Crossmembers are occasionally made up of at least two tube pieces which have to be solidly connected to one another. In order to take into account the demand for the highest possible stability and torsional and flexural rigidity, on the one hand, and the lowest possible weight, on the other hand, different materials of differing density are occasionally used for the various tube pieces.
In order to take into account the needs for the lowest possible weight, and without a loss in stability, the tube piece running in the region of the steering column can be produced from steel, whereas the crossmember on the passenger side can have a lighter tube piece made from a light metal, in particular made of aluminum, with both tube pieces being fixedly connected to one another.
Within the context of the present invention, the term “tube” or “tube piece” is to be understood in general terms, it being possible within the context of the present invention for these to have any desired cross-sectional shape, which may be round, angular or oval, for example. Similarly encompassed is a configuration of a tube piece which is open laterally in cross section, for example in a C, T or L shape and the like.
The crossmember disclosed in document WO 2008/034522 is based on the concept of solidly connecting the individual tube pieces, which typically consist of different materials, in particular of light metals or composite materials, by means of a respective socket arranged between two tube pieces and by an adhesive connection between the socket and the tubes. The socket is in this case in the form of a single-part magnesium die-cast component.
A connection between the socket and the tube pieces by adhesive bonding is, however, less suitable for large-scale or mass production of crossmembers owing to the time and cost involved in this connection technique. In addition, this connection technique has the disadvantage that material-bonding joining processes common for tube pieces consisting of metal, in particular steel tubes or aluminum tubes, for example welding processes, and the associated cost-effective production processes cannot be used for the production of crossmembers. This is because it is not readily possible to simply weld tube pieces made of steel and aluminum to the socket made of diecast magnesium. This is disadvantageous with respect to the production costs for a crossmember.
Document EP 2 112 054 A1 discloses a crossmember having a crossmember tube piece made of steel on the driver side and a crossmember tube piece made of aluminum on the passenger side, the two crossmember tube pieces being welded to one another directly by means of a CMT welded connection.
The connection of the crossmember parts made of steel and aluminum by a CMT welded connection is disadvantageous since this is complicated and expensive. In addition, a material-bonded welded connection between aluminum and steel is to be considered sceptically in terms of the stability of the crossmember.